Known in the art are connecting cables, the multiwire twisted conductor whereof is composed of wires, each bearing a coating serving to permit soldering and to protect the copper wires against corrosion, with said coating made, for example, of polyurethane (cf., Mayofis I. M., Chemistry of Dielectrics (in Russian), Moscow, 1981, p. 206). If the wires are to be soldered, one end of the conductor is immersed into molten tin, whereby the conductor length immersed into the melt undergoes tinning. However, in case of the multiwire twisted conductor of the foregoing design, the thickness of the polyurethane coating is not less than 10.mu., with the result that the wire diameter is large, and the enamel coating procedure is inefficient. Besides, the service dependability of the conductor in the soldered joint areas is low since the elastic polyurethane coating is at these points in contact with rigid sections coated with tin, and is susceptible to breakage in bending.
There is also known a multiwire twisted conductor, each wire whereof bears a coating applied through the full length to permit soldering and protection of the conductor against corrosion, comprising wires with said coating made of fusible metals or alloys (ref. Foreign-Made Connecting Wires, (in Russian), Moscow, 1963, p. 24). However, the above-mentioned multiwire twisted conductor is disadvantageous in low service dependability resulting from stiffness of the soldered joint (with the soldered joint extending at heating to the areas adjacent to the point of soldering), and also in excessive consumption of tin and excessive weight (with the thickness of the tin coating equal to 3 to 7.mu. whereas the thickness of the coating sufficient for high-quality soldering is nearly equal to that of a monomolecular layer).
Since the prior-art multiwire twisted conductors are used extensively, the losses of expensive and deficient tin are high, and the weight and size of cables increase because the wires bear the fusible metal coatings through the full length thereof, and not in local areas. In addition, the service dependability of the conductors decreases because the soldered joints extend to the adjacent areas.
There is known a device for tinning long-size products, such as wires, comprising a bath of melt, an immersion device for dipping the wire into the melt, and take-up and feed mechanisms (cf., USSR Inventor's Certificate No. 262575, Cl. C23C 1/14).
The prior-art device is disadvantageous in that the efficiency thereof is low, and the coating applied to the wire must invariably be continuous because of the constructional features of said device.
Also known is a device for wire coating, comprising a bath of melt, a wire immersion device disposed on the bath of melt, a take-up and feed mechanism, and a pass for removal of excess tin from the wire (cf., USSR Inventor's Certificate No. 546661, Cl. C23C 1/14).
A disadvantage also inherent in the foregoing device resides in low efficiency. Besides, the expenditure of coating material used during operation of said device is high because of a high coating thickness and variation in thickness of the coating.
The prior-art device does not provided for tinning of locally alternating areas of wire during continuous operating procedure.